A flange weight reduction pit is often designed on the flange face of an aluminum alloy wheel in order to reduce the weight, flange drainage channels are designed on two sides of the flange weight reduction pit, the inner drainage channel communicates with the weight reduction pit and a central hole, and the outer drainage channel communicates with the weight reduction pit and the outer edge of the flange. The surface of the flange is machined and turned, and the flange weight reduction pit and the flange drainage channels are cast, so after machining, many burrs remain at the handover positions of casting and machining at the edges of the weight reduction pit and the drainage channels; these burrs need to be cleaned manually one by one, and there are a lot of irregular weight reduction pits and drainage channels, so the burrs are difficult to remove and easily missing to scrape, and the removal efficiency is low.